Air motor governor



[72] Inventor Philip A. Snider Fort Wayne, Indiana [21 Appl. No. 686,599

[22] Filed Nov. 29, 1967 [45] Patented Oct. 27, 1970 [73] AssigneeDotco, Inc.

Hicksville, Ohio a corporation of Ohio [54] AIR MOTOR GOVERNOR 8 Claims,8 Drawing Figs.

52 US. Cl. 418/41; 137/56 [51] Int. Cl ..F0lc 13/02, FOlc 21/12 [50]Field of Search 91/76; 137/33, 56; 251/212 [56] References Cited UNITEDSTATES PATENTS 1,506,862 9/1924 Parsons 91/76 1,723,589 8/1929 Vanl-lamersveld 9l/76X 799,580 9/1905 Stapley 251/212 2,149,645 3/193991/76 2,598,439 5/1952 137/56 3,101,736 8/1963 Egger 251/212X FOREIGNPATENTS 1,257,773 2/1961 France 91/76 789,637 l/1958 Great Britain 91/76Primary Examiner-Everette A. Powell, Jr. Attorney Oberlin. Maky.Donnelly and Renner ABSTRACT: An air motor governor including a pair ofpivotally mounted blades having valve elements on one end biased apartby a spring to permit unrestricted flow of air therebetween atrotational speeds below a predetermined level, and weights on the otherend which are forced outwardly by centrifugal force at increased speedsto cause the valve elements to move together thereby cutting off aportion of the air flow.

Patented Oct. 27, 1970 Sheet INVENTOR PHIL/P A. s/v/om ATTORNEYSPatented Oct. 27, 1970 3,535,982

INVENTOR PHIL/P A. SlV/DER ATTORNEYS AIR MOTOR GOOR BACKGROUND OF THEINVENTION The present invention relates generally as indicated to an airmotor governor valve and more particularly to an improved governorconstruction for efficiently and effectively controlling the speed ofair-powered motors.

High speed hand tools such as grinders and the like operate mostefficiently when driven at a substantially constant speed which may bemaintained with the use of a suitable speed-control governor operativelyconnected to the air motor for the hand tool. However, the governorsthat are presently available for this particular purpose are generallyquite complicated and expensive to manufacture, being comprised of agreat many moving parts which not only add to the overall cost ofmanufacture, but also provide increased friction with consequent wearand poor response. Likewise, the governors are usually much too largefor use with small air motors, and even the large sized motors mayrequire major modification to receive the governors because of theirpoor capacity to size ratio which may greatly affect the size andappearance of the mo tor. Regardless of these modifications, thegovernors may unduly restrict the flow of air when fully open, thusreducing the power of the motor.

SUMMARY OF THE INVENTION With the foregoing in mind, it is a principalobject of the present invention to provide an air motor governor whichis more responsive and provides less restriction to air flow when fullyopen than previous known governors, and yet is quite compact and simplein construction, thereby greatly reducing the cost of manufacture andmaking it suitable for use with both small and large sized motors withlittle or no modifications required.

Another object is to provide such a governor with relatively few parts,and of a well-balanced design with minimum friction.

Still another object is to provide a governor of the type describedhaving a very high capacity to size ratio.

A further object is to provide such a governor in combination with anair motor having an adjustable air noule for permitting variations inthe maximum speed of the tool when the governor is fully closed.

These and other objects of the present invention may be accomplished byproviding the governor with a pair of pivotally mounted blades havingvalve elements on one end which are biased apart by a spring to permitsubstantially unrestricted flow of air therebetween when the speed ofthe governor is below a predetermined level, and having weights on theother end which are forced outwardly by centrifugal force as the speedincreases to move the valve elements toward each other thereby cuttingoff a portion of the air flow as required to maintain the air motor at asubstantially constant speed. The edges of the valve elements may becontoured to make use of the aerodynamic effects of the incoming air toimprove response, and the bearing surfaces about which the blades pivotmay be protected from the incoming air so as not to be afiected therebyor by foreign objects in the air.

The free end of each valve element is in mating engagement with anangularly disposed cam surface on the other valve element for keepingthe blades in phase with each other during pivotal movement of the valveelements between the fully open and fully closed positions.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail a certain illustrativeembodiment of the invention, this being indicative, however, of but oneof the various ways in which the principle of the invention may beemployed.

BRIEF DESCRIPTION OF THE DRAWING In the annexed drawing:

FIG. I is a fragmentary side elevation view of an airoperated handtoolof conventional type having portions thereof broken away to show themanner of attachment of the governor of the present invention to the airmotor;

FIG. 2 is an exploded isometric view of the governor of FIG. 1 showingthe various parts thereof in disassembled form;

FIG. 3 is a schematic top plan view of the air motor governor of FIG. 1showing the valve elements in the fully opened position, taken on theplane of the line 3-3;

FIGS. 4 and 5 are schematic top plan views similar to FIG. 3, butshowing the valve elements in the partially and fully closed positions,respectively;

FIG. 6 is an enlarged side elevation view of the governor of FIG. 1 withthe noule of the handtool shown in position closely adjacent to thevalve elements;

FIG. 7 is a fragmentary transverse section through such elements andnozzle, taken on the plane of the line 77 of FIG. 6; and

FIG. 8 is a fragmentary transverse section through the bearing mount forone of the valve elements of the governor, taken on the plane of theline 8-8, FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularlyto the drawing and first especially to FIG. I. there is shown by way ofexample an air operated handtool I which may be of conventional type.including a generally cylindrical housing 2 containing an air motor 3similar, for example, to that shown in US. Pat. No. 2,830,560. grantedto Roland E. Doeden on Apr. 15. I958 Projecting from one end of thecylindrical housing 2 is a sleeve 4 covering the chuck element forreleasably gripping the shank or arbor 5 on which a suitable tool suchas a grinding element may be mounted.

The other end of the cylindrical housing 2 has an end cap 6 threaded orotherwise connected thereto, and provided with a handle extension 7 towhich may be connected an air supply hose 8. An air-throttling sleeve 10or other such device may be mounted on the handle extension 7 forselectively opening and closing communication between the interior I] ofthe handle extension 7 and the air supply hose 8, from whence the airpasses through a central opening 12 in the end cap 6 into a cavity 13defined by the end cap 6 and the adjacent end of the air motor 3.

Within the cavity 13 there is disposed a speed-control governor valve 15constructed in accordance with this invention, which as clearly shown inFIGS. 28 comprises three main parts, a carrier or base plate 16; a pairof blades 17. 18 suitably pivotally mounted on said base plate; and aspring 19 interconnecting the blades 17, 18 in a manner and for apurpose to be subsequently fully explained. Pins 20 pressed intoopenings 21 on diametrically opposite sides of the base plate 16 providethe pivotal mounts for the blades l7, 18, such blades having sleeves 22brazed or otherwise secured thereto that are adapted to be telescopedover the pins 20. Recesses 25 (see especially FIG. 8) may be provided inthe inner ends of the sleeves 22 for receipt of hardened steel balls 26which provide bearing surfaces for the ends of the pins 20 to frictionand wear. The balls 26 may be permanently mounted within the recesses 25by peening over the edges of the recesses.

Each of the blades l7, 18 are desirably of the same generally V-shapeconfiguration, one of the arms 25 of the blades 17, 18 constituting avalve element 26, and the other arms 27 having weights 28 attachedthereto, which may be in the form of solid pins extending in the samegeneral direction as the pivot sleeves 22 and parallel thereto. Thesleeves 22 are attached to the blades 17, 18 at the intermediate section29 The inner edges 30, 31 of the arms 25, 27, respectively. arepreferably straight and intersect to provide an included angletherebetween somewhat greater than and preferably approximately 1 10with the inner edges 30 of the arms 25 and inner edges 31 of arms 27parallel to each other. The outer end 32 of the arm 25 for each blade isalso desirably straight and disposed at an angle so that it is parallelto the inner edge 31 of the arm 27 of the other blade for mating andsliding engagement therewith. Accordingly, when the blades i7, 18 areproperly assembled on the base plate 16 with the valve elements 26 inside by side relation and the inner edges 31 of the arms 27 extendingoutwardly adjacent the outer ends 32 of the arms 25 of the other bladesand in mating engagement therewith, as shown in FIGS. 3-5, the governor15 is substantially perfectly balanced, regardless of the position ofthe blades l7, 18 since the mating engagement between the inner edges ofthe arms 27 and the outer ends 32 of the blades serve to keep the blades17, 18 in phase with each other.

The valve elements 26 are yieldably maintained in the fully openposition with the outer ends 32 of the arms 25 in full mating engagementwith the inner edges of the arms 27 by the bias of the spring 19 asshown in FIG. 3 which may have its ends 35 hooked over the weights 28where they are confined in narrow notches 36 therein.

To install the governor 15 in the handtool l, the end cap 6 is removedand the base plate 16 is threadedly connected or otherwise attached tothe exposed end of the rotor shaft 37 for rotational movement therewith.At the same time, an air nozzle 38 threadedly received in the centralopening 12 in the end cap 6 may be axially adjusted to establish thedesired clearance 40 between the inner end 39 of the nozzle and theblades 17, 18 of the governor 15, for a purpose to be fully explainedhereafter. Now the end cap 6 is threaded into the cylinder housing 2,after which the air throttling sleeve may be moved to the on positionpermitting air to flow from the air supply hose 8 through the nozzle 38into the cavity 13. With the valve elements 26 fully open as shown inFIG. 3, the governor provides substantially no restriction to the airflow despite its relatively compact size which pemiits it to beinstalled in a cavity 13 of relatively small diameter and short length.For example, a governor 15 of the type disclosed herein for use with atwo horsepower air motor will operate in a cavity approximatelyeleven-sixteenths inch deep by l [/16 inch' diameter, with very littlerestriction to air flow when fully open. Thus, as can be seen, thegovernor 15 has a very high capacity to size ratio and because of itssize, it can be used to govern very small motors with little or nomodifications required which would affect the size or appearance of thetool.

The bias of the spring 19 should be sufficient to maintain the valveelements 26 in the fully open position up to the optimum speed for thetool, as for example i 1.000 r.p.m. At in creased speeds, the weights 28will be forced outwardly due to centrifugal force to cause the valveelements 26 to move closer together into overlying relationship with aportion of the nozzle 38 as shown in FIG. 4 (the noule being shown inphantom lines) thereby restricting the air flow into the cavity 13 andcausing a reduction in the speed of the motor. The extent of movement ofthe valve elements will be dependent upon the speed of rotation of themotor above the design speed; if the speed continues to increase thevalve elements 26 will completely close with the inner edges 30 indirect mating engagement with each other as shown in FIG. 5, permittingminimum air flow through the clearance 40 between the inner end 39 ofthe nozzle 38 and closed valve elements. The extent of the clearance 40which may be adjusted as aforesaid will thus regulate the maximum speedof the motor when the governor is fully closed.

From the above discussion, it can now be seen that the governor of thepresent invention is very simple in construction and has a minimumnumber of parts which are extremely simple and easy to manufacture.There are only two moving parts which provide a well-balanced design,and the bearing mounts for the movable parts reduce the friction to aminimum, thus improving the response of the governor and minimizingwear. The response may be further improved by beveling the inner edges30 of the valve elements 26 on the side opposite the nozzle 38 asperhaps best seen in FIG. 7 to make use of the aerodynamic effects ofthe incomin air.

Because of the location of the bearing surfaces 2 within the sleeves 22,they are protected from the incoming air which might otherwise form ashellac substance on these surfaces which could afiect the governorperformance. Likewise, foreign objects in the air cannot afiect thebearing mounts, and the governor is capable of giving excellent and safeperformance for an extended period of time. In the event of failure ofthe governor spring, the weights 28 will be forced radially outwardly bylow centrifugal force, causing the governor to shut off for fail-safeoperation.

I claim:

1. A governor valve comprising a base plate, a pair of blades pivotallymounted intermediate their ends on diametrically opposite sides of saidbase plate, said blades being of a generally V-shaped configurationformed by a pair of diverging arms which provide said ends of saidblades, one of said arms of each blade constituting a valve element andthe other of said arms of each blade having weights thereon, and springmeans interconnecting said other arms of said blades for biasing saidvalve elements apart, said weights at excessive rotational speeds ofsaid governor valve being forced outwardly by centrifugal force to causesaid valve elements to move toward each other, the inner edges of saidother arms of each blade being straight and substantially parallel toeach other, and the outer ends of said one arms also being straight andsubstantially parallel to the inner edges of said other arms of theother blade and in mating and sliding engagement therewith formaintaining said blades in phase with each other during pivotal movementtoward and away from each other.

2. The governor valve of claim 1 wherein the inner edges of said onearms of said blades are also straight and substantially parallel to eachother for direct mating engagement with each other during movement ofsaid valve elements toward each other, and the inner edges of both armsof each of said blades intersect to provide an included angletherebetween greater than 3. The governor valve of claim 2 wherein saidincluded angle is approximately 1 10.

4. The governor valve of claim 1 wherein said base plate has a pair ofpins projecting therefrom, and each of said blades has a sleeve attachedthereto intermediate said arms which is telescoped over said pins toprovide such pivotal mounts for said blades, said sleeves havingrecesses in their inner ends for receipt of hardened metal balls whichprovide bearing surfaces for the ends of @d pins to minimize frictionand wear.

5. The governor valve of claim 1 wherein the inner edges of said valveelements are straight and beveled to provide an aerodynamic surface forimproved response.

6. The governor valve of claim 1 wherein said weights are in the form ofsolid pins, said solid pins having notches therein for receipt of thehooked ends of said spring means.

7. The governor valve of claim 1 further comprising means mounting saidbase plate for rotation adjacent an air passage for controlling the airflow through said air passage by movement of said valve elements towardand away from each other into and out of overlying relation with saidair passage, and an axially adjustable air nozzle in said air passagefor varying the clearance between said valve elements and nozzle throughwhich air continues to flow when said valve elements are completelyclosed.

8. The governor valve of claim 1 wherein said inner edges of said otherarms limit movement of said one arms away from each other by engagementby the outer ends of said one arms with said inner edges.

